Mars moves into rebellious Aquarius on December 25th. Uranus (the ruler of Aquarius) in Aries (ruled by Mars) will be hitting the Capricorn Sun with an exact square (4 degrees) on the same day. This is a recipe for disruption, but it's also a chance to bust out of some old, holiday habits.
Aquarius/Uranus and Mars/Aries together will be incredibly restless, edgy and irritable. This energy can trigger arguments, and possibly some accidents. Give yourself and others plenty of room to move. Dial down the expectations. Note that the emphasis is on liberation (instead of rules) and the larger group (instead of your intimate circle). You may be compelled to take a look beyond your immediate family.
The upside is this: if Christmas is a difficult time for you (depressing, isolating, overwhelming) you can use this energy to break free. Many people find this time of year challenging because of its association with the past. Uranus/Aquarius is all about the future, so start your own traditions.